Small enterprise environments typically desire telephone systems that provide a variety of communication features. For example, small enterprise environments typical desire telephones systems that provide internal intercom calls from one telephone terminal to another telephone terminal within the telephone system while still supporting external public switched telephone network (PSTN) calls between a telephone terminal within the system and an external telephone system connected to the PSTN. Other features desired by small enterprise environments may include call conferencing, call transferring, and voice mail functions. Due to the growth expectations and lack of dedicated IT personnel in small enterprises, there is a desire for such telephone systems to be readily expandable, require little-to-no manual configuration, and require little-to-no special wiring.